One possible storyline could be that they face a lot of family drama. Their families might be shocked and have different reactions, some may be supportive while others are against it. It could also explore how Ben and Gwen deal with the sudden responsibility and how it changes their relationship from just being cousins to co - parents.
Another storyline might involve them hiding the pregnancy at first. They could be afraid of the judgment from their friends and society in general. As the pregnancy progresses, it becomes harder to hide, and they have to start thinking about how to break the news. This could lead to a series of events where they learn more about themselves and each other, and also about the importance of honesty and support in difficult situations.
Maybe in the fanfiction, there could be an external factor that led to this situation. For example, some kind of alien influence or a magical accident. Then the story could focus on them trying to find a way to reverse it while also coming to terms with the fact that they are about to have a child. They would have to make decisions about their future, like whether they should continue their normal lives or focus entirely on the new family they are creating.
One possible plotline could be that they face unexpected challenges due to the pregnancy at a young age. Maybe they have to deal with the reactions of their family and friends. Another could be that they embark on a journey to find a way to ensure the well - being of the unborn child in a world full of dangers they usually face.
It's not common at all. Most fanfiction tends to follow the more positive and popular pairings or storylines within the fandom. The idea of Ben getting Gwen pregnant is rather controversial due to their family relation in the source material. Writers usually prefer to write about things that are more in line with the general mood and values of the fan community, which doesn't really include this kind of rather odd and potentially uncomfortable scenario.
One possible storyline could be about Gwen facing the challenges of being a superhero while pregnant. She might have to deal with villains who try to take advantage of her condition. Another could be her preparing for the arrival of the baby, like setting up a nursery with her friends and family's help. And also, there could be a story where she discovers new powers related to her pregnancy that help her protect herself and the unborn child.
One possible storyline could be that it's set in an alternate future where Ben and Gwen are married. Gwen discovers she's pregnant and they both have to deal with the excitement and nervousness of impending parenthood. They might start preparing for the baby, like decorating a nursery and thinking about names.
One possible storyline could be that Harry is cursed by a dark wizard. The curse has the unexpected side - effect of making him pregnant. He then has to search for a way to break the curse while dealing with the physical and emotional turmoil of pregnancy. Another could be that it's a result of some experimental magic gone wrong. He might have been trying to help someone with a fertility spell and it backfired on him.
One interesting storyline could be Ben and Gwen having to face a new, powerful alien threat that they've never encountered before. They might have to combine their unique skills and powers to defeat it.
In this fanfiction, it could be that Sasuke returns to the village and he and Sakura start to build a life together. Their friends are happy for them, and then Sakura becomes pregnant. The story might explore how the news affects their friends and family, and also how Sasuke and Sakura grow as a couple during this time.
One possible storyline could be that they discover the pregnancy unexpectedly. Maybe they are in the middle of some sort of adventure or struggle against a common enemy, and this new development completely changes their priorities and how they interact with each other. They might start to plan for a more stable future, away from the chaos they were previously in.
One possible storyline could be the challenges Bella and Edward face as they prepare for a new life together while dealing with the vampire - human relationship issues. Maybe they struggle to keep Bella safe during her pregnancy considering her human frailty.
In the fanfiction, the relationship between Ben and Gwen could change in a complex way. The news of the pregnancy might initially cause some tension and fear between them. But as they gradually accept the situation, they start to grow closer. They might start to see each other in a new light, not just as partners in adventure but as life - long partners in raising a child. This could involve a lot of communication, understanding, and compromise as they navigate through this new chapter of their lives together.